Radiation detecting element and method of manufacturing the same

ABSTRACT

The present invention provides a method of preventing or reducing X-ray-induced temporal changes of a semiconductor photoelectric conversion film formed on a TFT substrate, in which a protective film or sheet is used to protect the semiconductor photoelectric conversion film in order to improve weather resistance such as light blocking effect and moisture resistance. 
     The present invention provides a radiation detecting element characterized by including a substrate having a plurality of pixel areas formed thereon, each having at least one switching element and at least one charge storage capacity, a photoelectric conversion film formed on the individual pixel areas for converting radiation into electrical charge, a protective film individually covering the photoelectric conversion film and having an area that is substantially the same as or larger than that of at least the photoelectric conversion film and a seal member and a sealant arranged so as to enclose the photoelectric conversion film, for fixing the protective film.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCTINTERNATIONAL APPLICATION PCT/JP01/02551.

TECHNICAL FIELD

The present invention relates to a radiation detecting element and amethod for manufacturing the same for improvement of moisture resistanceand light resistance and mechanical protection of a photoelectricconversion film.

BACKGROUND ART

X-ray penetration images for medical or industrial applications werephotographed using X-ray films. Subsequently, sensors emerged whichconvert an image directly into an electric signal without using anyX-ray films. Such sensors include, for example, image pickup devicesusing an X-ray image intensifier+an image pickup tube or CCD, orsmall-sized image pickup elements such as CCDs having a photodiode aswell as a scintillator provided thereon. Furthermore, in recent years,large-sized two-dimensional X-ray sensors (X-ray flat panel sensors)have been developed using a TFT (thin film transistor) technology usedfor liquid crystal displays.

These X-ray sensors include a type that uses a scintillator to covert anX ray into light and then uses a photodiode to convert the light intoelectricity, and a type that uses a semiconductor photoelectricconversion film to convert an X ray directly into an electric signal.

In these X-ray sensors, some scintillators or semiconductorphotoelectric conversion films have a hygroscopic property and mayconsequently have their characteristics degraded. In particular, for thesemiconductor photoelectric conversion films, absorbed moisture reduceselectric resistance to cause a large leakage current to flow, therebydegrading their characteristics or causing a short circuit.

CCDs are so small as to be entirely packaged easily. Further, asdisclosed in Patent Nos. 03-029873 and 03-077941, a configurationprovided with a protective film is known in which a moisture resistiveresin that can be formed into a film by vapor deposition on a CCD isformed into a film directly on a scintilator. All the disclosures inPatent Nos. 03-029873 and 03-077941 are incorporated herein by referencein their entirety.

FIG. 5 is a partial sectional view of a CCD packaged using theabove-mentioned conventional techology. As shown in the figure, theabove-mentioned configuration comprises light-receiving elements 52 anda signal line 53 arranged on a substrate 51, a passivation film 55 thatprotects the light-receiving elements 52 and the signal line 53, ascintillator 57 provided on the passivation film 55 so as to correspondto the top of the light-receiving elements 52, a protective film 511formed so as to cover the scintillator 57 and the passivation film 55,and a sealing resin 512 provided at an end of the protective film 511corresponding to the junction between the passivation film 55 and theprotective film 511. Further, at an end of the CCD, a bonding pad 54 isprovided on a main surface of the substrate 51 to connect the signalline 53 to an external portion. Furthermore, the protective film 511 hasa three-layered structure including a non-moisture-permeable metal layer59 an resin layers 510 and 58 that sandwich the metal layer 59therebetween.

However, with this configuration, the protective film 511 is formed byplasma CVD, so that after all the films of entire CCD, including theback and side surfaces of the substrate 1, have been formed, films mustbe removed which have been formed on the back surface of the substrate 1and on the bonding pad 54 in a peripheral portion of the passivationfilm 55. As a result, the process of producing the CCD has difficulties.

Further, with the above described technology, the protective film 511,formed by plasma CVD, is in tight contact with the scintillator 57.Accordingly, if external pressure is exerted on the protective film, itis reached to the scintillator 57 through the protective film to affectthe physical resistance of the X-ray conversion film.

Furthermore, at the junction between the substrate and the protectivefilm, the main surface of the substrate 51 is joined to the resin layers510 and 58 of the protective film 511, with the junction sealed with thesealing resin 512, as shown in FIG. 5. However, the sealing resin 512 isjointed to the resin layers 510 and 58 of the protective film 511, andmoisture may invade the scintillator 57 through this junction.Consequently, this structure does not have sufficient moistureresistance. Another problem is that a large amount of time and labor isrequired to produce the protective film 511 of the layered structure.

On the other hand, for large-sized x-ray sensors using the TFTtechnology, the method of packaging the entire substrate has thedisadvantages of an operation process, insufficient airtightness, andthe like. Further, the maintenance or the like of these X-ray sensors isvery cumbersome. Accordingly, the method of packaging the entiresubstrate is not appropriate for the large-sized X-ray sensor using theTFT technology.

Another problem is that both the CCD and the large-sized X-ray sensorusing the TFT technology require separate material for covering, thusincreasing costs.

DISCLOSURE OF THE INVENTION

The present invention is provided to solve the above described problems,and it is a basic object thereof to provide radiation detecting elementand a manufacturing method therefor which enable a photoelectricconversion film formed on a substrate to be covered so as to reliablyprovide moisture resistance and which also enable this film to be easilyformed.

One aspect of the present invention is a radiation detecting elementcomprising:

a substrate having at least individual electrodes corresponding to pixelareas;

converting means, formed on an image area comprising said pixel areas,of converting radiation into electricity;

a common electrode arranged on said image area and corresponding to saidindividual electrodes; and

non-moisture permeable covering means of covering said individualelectrodes, said common electrode, and said converting means and fixedto a surface of said substrate on which said image area is formed, andin that:

an interval of a predetermined size is formed between said coveringmeans and said common electrode.

Another aspect of the present invention is a radiation detecting elementcomprising:

a substrate having at least individual electrodes corresponding to pixelareas;

converting means, formed on an image area comprising said pixel areas,of converting radiation into electricity;

a common electrode arranged on said image area and corresponding to saidindividual electrodes;

covering means of covering said individual electrodes, said commonelectrode, and said converting means and fixed to a surface of saidsubstrate on which said image area is formed, the covering means havinga three-layered structure in which a non-moisture permeable layer issandwiched between two other layers; and

non-moisture permeable sealing means of sealing a peripheral portion ofsaid covering means, and in that:

in the peripheral portion of said covering means, said sealing means andthe non-moisture permeable layer of said covering means are in directlytight contact with each other.

Still another aspect of the present invention is a radiation detectingelement comprising:

a substrate having at least individual electrodes corresponding to pixelareas;

converting means, formed on an image area comprising said pixel areas,of converting radiation into electricity;

a common electrode arranged on said image area and corresponding to saidindividual electrodes;

non-moisture permeable covering means formed only on said commonelectrode; and

non-permeable sealing means of sealing an area extending from aperipheral portion of said covering means to a surface of saidsubstrate.

Yet still another aspect of the present invention is the radiationdetecting element comprising:

a substrate having at least individual electrodes corresponding to pixelareas;

converting means, formed on an image area comprising said pixel areas,of converting radiation into electricity;

a common electrode arranged on said image area and corresponding to saidindividual electrodes; and

non-permeable sealing means of sealing an area extending from aperipheral portion of said common electrode to a surface of saidsubstrate, and in that:

said common electrode has non-moisture permeability.

Still yet another aspect of the present invention is the radiationdetecting element, wherein said converting means is a semiconductorphotoelectric conversion film.

A further aspect of the present invention is the radiation detectingelement, wherein said semiconductor photoelectric conversion film isamorphous selenium, iodide, bromide, or telluride, or any mixturethereof.

A still further aspect of the present invention is the radiationdetecting element, wherein said converting means has a scintillator anda photodiode.

A yet further aspect of the present invention is the radiation detectingelement, wherein said scintillator has thallium-activated sodium iodide(NaI (T1)), thallium-activated cesium iodide (CsI (T1)),sodium-activated cesium iodide (CsI (Na)), or bismuth gemanate (B1₄Ge₃O₁₂), or any mixture thereof.

A still yet further aspect of the present invention is the radiationdetecting element, wherein said covering means is glass.

An additional aspect of the present invention is the radiation detectingelement, wherein said glass blocks of ultraviolet rays and visible lightof short wavelengths belonging to a blue area.

A still additional aspect of the present invention is the radiationdetecting element, wherein said covering means has a layered structure.

A yet additional aspect of the present invention is the radiationdetecting element, wherein said layered structure includes a resin layerand a metal or glass layer.

A still yet additional aspect of the present invention is a manufacturemethod for a radiation detecting element comprising the steps of:

forming at least individual electrodes corresponding to pixel areas, onsubstrate;

forming converting means of converting radiation into electricity, on animage area comprising said pixel areas;

arranging a common electrode corresponding to said individualelectrodes, on said image area; and

fixing non-moisture permeable covering means of covering said individualelectrodes, said common electrode, and said converting means, to asurface of said substrate on which said image area is formed, and inthat:

an interval of a predetermined size is formed between said coveringmeans and said common electrode.

A supplementary aspect of the present invention is a manufacture methodfor a radiation detecting element comprising the steps of:

forming at least individual electrodes corresponding to pixel areas, ona substrate;

forming converting means of converting radiation into electricity, on animage area comprising said pixel areas;

arranging a common electrode corresponding to said individualelectrodes, on said image area;

fixing covering means of covering said individual electrodes, saidcommon electrode, and said converting means, to a surface of saidsubstrate on which said image area is formed, the covering means havinga three-layered structure in which a non-moisture permeable layer issandwiched between two other layers; and

sealing a peripheral portion of said covering means using non-moisturepermeable sealing means, and in that:

in the peripheral portion of said covering means, said sealing means andthe non-moisture permeable layer of said covering means are in directlytight contact with each other.

A still supplementary aspect of the present invention is a manufacturemethod for a radiation detecting element comprising the steps of:

forming at least individual electrodes corresponding to pixel areas, ona substrate;

forming converting means of converting radiation into electricity, on animage area comprising said pixel areas;

arranging a common electrode corresponding to said individualelectrodes, on said image area;

forming non-moisture permeable covering means only on said commonelectrode; and

sealing an area extending from a peripheral portion of said coveringmeans to a surface of said substrate, using non-permeable sealing means.

A yet supplementary aspect of the present invention is a manufacturemethod for a radiation detecting element comprising the steps of:

forming at least individual electrodes corresponding to pixel areas, ona substrate;

forming converting means of converting radiation into electricity, on animage area comprising said pixel areas;

arranging a common electrode corresponding to said individualelectrodes, on said image area; and

sealing an area extending from a peripheral portion of said commonelectrode to a surface of said substrate, using non-permeable sealingmeans, and in that:

said common electrode has non-moisture permeability.

As described above, the present invention uses 1) a method of using athin glass plate as a seal member to seal the entire photoelectricconverting section, 2) a method of using a sheet composed of a metal andresin layers to seal the photoelectric converting section, 3) a methodof forming a metallic thin film on an opposite electrode of aphotoelectric conversion film to improve moisture resistance, or 4) amethod of making a glass container with a dented central portion toimprove moisture resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a)-1(e) are diagrams showing a configuration and a manufactureprocess according to a first embodiment of the present invention;

FIGS. 2(a)-2(e) are diagrams showing a configuration and a manufactureprocess according to a second embodiment of the present invention;

FIG. 3(a)-3(e) are diagrams showing a configuration and a manufactureprocess according to a third embodiment of the present invention;

FIG. 4(a)-4(c) are diagrams showing a configuration and a manufactureprocess according to a fourth embodiment of the present invention; and

FIG. 5 is a partial sectional view showing the configuration of a CCDaccording to the prior art.

DESCRIPTION OF SYMBOLS

-   1 Substrate-   2 Pixel area-   3 Lead wired area-   4 Photoelectric conversion film-   5, 25 Common opposite electrode-   6, 29 Protective film-   7 Seal member-   8 Sealant-   26 Protective metallic thin film-   36 Protective cover

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the drawings.

(Embodiment 1)

FIG. 1 shows a radiation detecting element according to Embodiment 1 ofthe present invention, and a manufacture process therefor, shownstep-by-step. In FIG. 1(a), a substrate 1 composed of glass has a pixelarea 2 and a lead wired area 3 formed thereon. The pixel area has aplurality of pixels two-dimensionally formed therein. Each pixel has atleast one pixel area and at least one charge storage capacity formedtherein. On the pixel area 2, a photoelectric conversion film 4 isformed, and on the photoelectric conversion film 4, a common oppositeelectrode 5 is formed which has substantially the same size as thephotoelectric conversion film. A protective film 6 is provided thereonand has a peripheral portion isolated from the exterior by a seal member7 or by the seal member 7 and a sealant 8. In this case, the protectivefilm 6 is arranged so as to form a predetermined interval between itselfand the photoelectric conversion film. Accordingly, the photoelectricconversion film 4 and the common opposite electrode 5 are arranged inthe space formed by the pixel area 2, the lead wired area 3, the sealmember 7, the protective film 6, and the sealant 8.

Next, the manufacture method for the radiation detecting elementaccording to this embodiment will be described with reference to FIGS.1(b) to 1(e).

In FIG. 1(b), the substrate 1 composed of glass has the pixel area 2 andthe lead wired area 3 formed thereon. In a basic structure, the pixelarea has a TFT switching element, a charge storage capacity, and anelectrode as in a substrate used for a liquid crystal display.

In the pixel area 2, the photoelectric conversion film 4 is made of asemiconductor film to convert the energy of an X ray into charges(electrons and holes) and store the amount of charges generated in thecharge storage capacity so that a switching circuit using TFTs can takeout this amount as an electric signal through the lead wired area 3.Further, the lead wired area 3 is pad for TAB packaging. Although notillustrated, the photoelectric conversion film 4 is connected to thepixel area via split electrodes on the pixel area. Further, thephotoelectric conversion film 4 has a common opposite electrode 5 formedthereon and corresponding to and shared by all the split electrodes onthe pixel area. The common opposite electrode 5 is connected tohigh-voltage wiring on the substrate 1. Materials for the photoelectricconversion film 4 may include iodide such as amorphous selenium (a-Se),mercury iodide (HgI₂), lead iodide (PbI₂), thallium iodide (TlI₂), orbismuth iodide (BiI₃), bromide such as mercury bromide (HgBr₂), leadbromide (PbBr₂), thallium bromide (TIBr₂), or bismuth bromide (BiBr₃),telluride such as cadmium telluride (CdTe) or cadmium zinc telluride(CdZnTe), and a mixture thereof. However, since a TFT substrate has anupper-limit temperature of about 250°C., the photoelectric conversionfilm may be formed of iodide such as amorphous selenium (a-Se), mercuryiodide (HgI₂), lead iodide (PbI₂), thallium iodide (TlI₂), or bismuthiodide (BiI₃), or bromide such as mercury bromide (HgBr₂), lead bromide(PbBr₂), thallium bromide (TlBr₂), or bismuth bromide (BiBr₃). Thesubstrate 1, pixel area 21 lead wired area 3, and photoelectricconversion film 4, used in FIG. 1, are the same as those used in thesubsequent description.

Now, FIG. 1(b) shows that the photoelectric conversion film 4 has beenformed on the pixel area 2. Although not illustrated, the photoelectricconversion film 4 is connected to the pixel area via the splitelectrodes on the pixel area. Further, the photoelectric conversion film4 has the common opposite electrode 5 formed thereon and connected tothe high-voltage wiring on the substrate 1.

Next, FIG. 1(c) shows that the seal member 7 has been formed on the leadwired area 3 in the periphery of the photoelectric conversion film 4. Asshown in this figure, the seal member 7 is formed to have a largerheight from the lead wired area 3 than the main surface of the commonopposite electrode 5. To form the seal member 7, a seal member extrudingapparatus is used to linearly draw it as in the case with a liquidcrystal display assembly process. To control the height of the sealmember 7, a filler such as bead-like or cylindrical pieces of glass orSiO₂ ceramics of the same diameter, which have already been mixedtogether, can be filled into the seal member 7 and pressurized forsetting after the protective film 6 has been stuck to the seal member 7.Suitable materials for the seal member 7 include a heat setting epoxyadhesive, room temperature setting epoxy material, heat setting acrylicmaterial, and ultraviolet setting acrylic material. The seal member 7may also be formed of glass material.

Next, FIG. 1(d) show that the protective film 6 has been placed on theseal member 7. The most easily available material for the protectivefilm 6 is a glass plate. A glass plate of 1 mm or less thickness issubstantially flexible if the substrate 1 is large in area. When thepressure in the space between the protective film 6 and the substrate 1is slightly reduced, the protective film 6 is sucked to the commonopposite electrode 5 and can thus be stably positioned.

Furthermore, when the seal member 7 is set in this state, the protectivefilm 6 is fixed with a gap of a predetermined size between itself andthe common opposite electrode 5. In this case, if the filler filled intothe seal member 7 has a diameter equivalent to or slightly larger thanthe thickness of the photoelectric conversion film 4, pressure-induceddamage to a peripheral portion of the photoelectric conversion film 4can be reduced even if the seal member 7 is set under a reducedpressure.

Next, FIG. 1(e) shows an example in which a peripheral portion of theprotective film 6 is sealed with the sealant 8 via the seal member 7 inorder to improve airtightness and moisture resistance. Materials for thesealant 8 may include silicone- and epoxy-based resins such as siliconoxide, silicon nitride, glass beads, and ceramic beads into which amaterial that is not penetrated by moisture is densely filled.

Thus, according to the radiation detecting element and manufacturemethod therefor according to this embodiment, the protective film 6, theseal member 7, and the sealant 8 can be provided with improved moistureand environmental resistance.

In this respect, light resistance can further be improved by forming theglass material used for the protective film 6 using UV cut glass,colored glass, or the like or further forming a metallic thin film onthe surface of the glass material.

(Embodiment 2)

FIG. 2 shows a radiation detecting element according to Embodiment 2 ofthe present invention, and a manufacture process therefor, shownstep-by-step.

In FIG. 2(a), the same reference numerals as those in FIG. 1 denote thesame or equivalent parts. Further, reference numeral 16 denotes aprotective sheet comprising a metallic thin film 16 a sandwiched betweenresins 16 b and 16 c. The radiation detecting element according to thisembodiment is constructed similarly to Embodiment 1 except that theprotective sheet 16 is the member covering the common opposite electrode5 and photoelectric conversion film 4. Thus, this difference will bemainly described below.

The manufacture method for the radiation detecting element according tothis embodiment will be described with reference to FIGS. 2(b) to 2(e).

FIG. 2(b) shows that the seal member 7 has been formed on the lead wiredarea 3 in the periphery of the photoelectric conversion film 4. To formthe seal member 7, a seal member extruding apparatus is used to linearlydraw it as in a liquid crystal display assembly process, as describedpreviously.

Next, FIG. 2(c) shows a step of covering the photoelectric conversionfilm 4 with the protective sheet 16 and providing the seal member foradhesion and sealing.

FIG. 2(d) shows that the sealant 8 has been provided to seal thestructure in order to improve the moisture resistance of the sealportion.

In this embodiment, the protective sheet 16 comprises the metallic thinfilm 16 a such as Al sandwiched between the resins 16 b and 16 c asdescribed above. A characteristic of this structure is that the metallicthin film 16 a can block light and the moisture-resistant resins 16 band 16 c are insulated. The metallic thin film 16 a is generally formedof Al. Further, the metallic thin film 16 a maybe formed byvapor-depositing the appropriate material on a resin sheet orsandwiching a metallic foil between resins.

The presence of the metallic thin film 16 a substantially improvesenvironmental resistance such as light blocking effect and moistureresistance, and this improvement is facilitated by using the metallicfoil. Since the metallic thin film 16 a serves to provide environmentalresistance such as significant light blocking effect and moistureresistance, the composition of the resins 16 b and 16 c is notparticularly limited. However, as shown in FIG. 2(e), the resins 16 band 16 c are further constructed so that that part of the resin 16 b Inthe top surface of the protective sheet 16 which corresponds to an endof the protective sheet 16 is peeled off expose a part of the metallicthin film 16 a. Then, the exposed part is sealed with the sealant 8.This improves the non-moisture permeability of the end of the junctionbetween the protective sheet 16 and the substrate 1, thereby furtherimproving the non-moisture permeability and environmental resistance ofthe protective sheet 16.

Further, in the above described embodiment, the protective sheet 16 andthe common opposite electrode 5 are arranged so as to have apredetermined distance therebetween, as in Embodiment 1. However, theprotective sheet 16 and the common opposite electrode 5 may be arrangedin contact with each other.

(Embodiment 3)

FIG. 3 shows a radiation detecting element according to Embodiment 3 ofthe present invention, and a manufacture process therefor, shownstep-by-step.

In FIG. 3(a), the same reference numerals as those in FIG. 1 denote thesame or equivalent parts. Further, reference numeral 25 denotes a commonopposite electrode, 26 is a protective metallic thin film, and 29 is aprotective film. The radiation detecting element according to thisembodiment basically has same construction and effects as the abovedescribed embodiments, but differs therefrom in that the protectivemetallic thin film 26 is provided on the common opposite electrode 25and has its end sealed with the sealant 8, and the protective film 29covers a portion including the protective metallic thin film 26 and thesealant 8.

That is, in this embodiment, the protective metallic thin film 26 isused as the protective film in each of the above described embodimentsto provide moisture resistance, light blocking effect, and insulatingproperties. Consequently, the protective film 29 is used to cover theprotective metallic thin film 26, the high-voltage portion of which isotherwise exposed to the exterior, the sealant 8, and a part of the leadwired area 3.

The manufacture method for the radiation detecting element according tothis embodiment will be described with reference to FIGS. 3(b) to 3(e).

FIG. 3(b) shows that the common opposite electrode 25 has been formed onthe photoelectric conversion film 4. In this case, the material used forthe common opposite electrode 25 is limited by the semiconductormaterial used for the photoelectric conversion film 4. This is becausethe photoelectric conversion film 4 must be sensitive over its thicknessin order to obtain a sufficient sensitivity for X rays. The necessity ofsuch a sensitivity means that in the interface between the electrode andthe semiconductor, no barrier is generated but an ohmic or similarjunction must be achieved. Whether an ohmic junction or a barrier isobtained depends on the combination of the material for thesemiconductor and the metallic material used for the electrode.

However, it is generally difficult to form thick electrode film using ametallic material allowing an ohmic junction to be formed, so that afirm common opposite electrode 25 is obtained by forming a metallic thinfilm allowing an ohmic junction to be formed and further forming, on theprotective metallic thin film 26, a metallic thin film such as Al whichis easy to form (the step shown in FIG. 3(c)).

Next, FIG. 3(d) shows how the peripheral portions of the photoelectricconversion film 4, on which the protective metallic thin film 26 hasbeen formed, and of the common opposite electrode 25 are sealed with thesealant 8. In this state, the protective metallic thin film 26 and thesealant 8 serve to provide the structure with non-moisture permeabilitysimilar to that in the above described conventional example.

However, in this state, the high-voltage portion of the protectivemetallic thin film 26 which is electrically connected to the commonopposite electrode 25 is exposed to the exterior. Further, if thematerial for the protective metallic thin film 26 is metal such as Cu,its surface may show a chemical reaction in the atmosphere to startdegrading the protective metallic thin film 26 via a gap in the sealant27, thereby reducing the sealing function.

Thus, as shown in FIG. 3(e), to improve the state in FIG. 3(d), theprotective film 29 is formed on the protective metallic thin film 26. Atthis time, the protective film 29 collectively covers the main surfaceof the protective metallic thin film 26, which is exposed to theexterior, the sealant 8, and a part of the lead wired area. Theprotective film 29 prevents the high-voltage portion from being exposed,while preventing the protective metallic thin film 26 from beingdegraded, thereby further reliably providing the structure withnon-moisture permeability.

In the above embodiments, the common opposite electrode 25 and theprotective metallic thin film 26 are stacked together to improvenon-moisture permeability. However, the protective metallic thin film 26may be omitted provided that the common opposite electrode 25 iscomposed of a metallic material which allows an ohmic junction to beformed and which can still be formed to have a sufficient thickness. Inthis case, the common opposite electrode 25 also acts as covering meansof the present invention which has the function of a protective film forproviding the structure with non-moisture permeability.

Further, in the above description, the protective metallic thin film 26is made of metal. However, the covering means of the present inventionis not limited to this material, but the protective metallic in film 26may be composed of another material such as glass as long as it is onlyplaced or the common electrode and has non-moisture permeability. Inthis case, the arrangement corresponding to the protective film 29 maybe omitted, or the protective film 29 need not necessarily cover allpositions corresponding to the protective metallic thin film 26 but hasonly to cover at least the boundary between the protective metallic thinfilm 26 and the sealant 8.

Further, in the above description, the protective film 29 is in contactwith the protective metallic thin film 26, but an interval of apredetermined size may be formed between the protective film 29 and theprotective metallic thin film 26. In this case, the protective film 29can absorb externally applied force, thereby preventing physical forcefrom being exerted on the protective metallic thin film 26, commonopposite electrode 25, and photoelectric conversion film 24.

(Embodiment 4)

FIG. 4 shows a radiation detecting element according to Embodiment 4 ofthe present invention, and a manufacture process therefor, shownstep-by-step.

In FIG. 4(a), the same reference numerals as those in FIG. 1 denote thesame or equivalent parts. Further, reference numeral 36 denotes aprotective cover. The radiation detecting element according to thisembodiment basically has a configuration and effects similar to those ofEmbodiment 1 but differs therefrom in that a protective cover 36 stuckto the substrate with the seal member 7 covers the photoelectricconversion film 4 together with the common opposite electrode 5,provided thereon.

FIG. 4(b) shows that the seal member 7 has been formed on the lead wiredarea 3 in the periphery of the photoelectric conversion film 4. Thismethod is similar to that of the other embodiments, described above.

FIG. 4(c) shows that the element has been completed by sticking theprotective cover 36 to the surface of the seal member 7.

In addition to the effects of Embodiment 1, this embodiment has thefollowing effect: The protective cover 36 has a certain height, so thateven if external pressure is applied to the radiation detecting element,the protective cover 36 acts as a buffer that absorbs the pressure,thereby protecting the photoelectric conversion film 4 and commonopposite electrode 5, both located inside the cover. This alsoeliminates the need to mold a high seal member 7, thereby simplifyingthe process.

In this embodiment, the protective cover 36 is made of resin, but toimprove moisture resistance and light blocking effect, a metallic thinfilm may be coated on the inner wall of the protective cover 36 so thatthe protective cover has a two-layered configuration. However, since thephotoelectric conversion film 4 has an opposite electrode 5 providedthereon and to which a high voltage is applied, either surface of thephotoelectric conversion film 4 must be coated with resin or the gapmust be widened in order to prevent a short circuit.

Further, as in the case with Embodiment 1, a sealant may span the sealmember 7, the lead wired area 3, and the end of the protective cover 36in order to further improve non-moisture permeability.

In the above described embodiments, the protective film 6, protectivesheet 16, seal member 7, protective metallic thin film 26, andprotective cover 36 are examples of the covering means of the presentinvention. The opposite common electrode 5 and common opposite electrode25 are examples of the common electrode of the present invention. Thesealant 8 is an example of the sealing means of the present invention.

Further, in the above description, the covering means of the presentinvention is composed of two layers of metal and resin or three layersof resins and metal sandwiched therebetween. However, the number oflayers is not limited to this aspect but may be arbitrary as long as thestructure can maintain non-moisture permeability. Furthermore, if thecovering means of the present invention is implemented as glass, itdesirably blocks ultraviolet rays and visible light of short wavelengthsbelonging to a blue area.

Moreover, in the above described embodiments, the pixel area 2, thephotoelectric conversion film 4, and the common opposite electrode 5 areused as a radiation detecting element to convert an incident X raydirectly into electricity. However, the converting means of the presentinvention may have a scintillator and a photodiode so that thescintillator converts an incident X ray into light, which is thenconverted into electricity by the photodiode. In this case, the materialfor the scintillator is thallium-activated sodium iodide (NaI (Tl)),thallium-activated cesium iodide (CsI (Tl)), sodium-activated cesiumiodide (CsI (Na)), or bismuth gemanate (Bi₄Ge₃O₁₂), or any mixturethereof. In short, the converting means of the present invention hasonly to be able to convert radiation into electricity, and is notlimited by the contents of the converting process.

INDUSTRIAL APPLICABILITY

As described above, the present invention relates to a radiationdetecting element and a manufacture method therefor which have veryexcellent effects of improving moisture resistance, weather resistance,and light blocking effect.

1. A radiation detecting element comprising: a substrate having a leastindividual electrodes corresponding to pixel areas; converting means,formed on an image area comprising said pixel areas, of convertingradiation into electricity; a common electrode arranged on said imagearea and corresponding to said individual electrodes; a seal memberdisposed from a periphery of said converting means; and non-moisturepermeable covering means of covering said individual electrodes, saidcommon electrode, and said converting means and fixed to a surface ofsaid substrate on which said image area is formed; wherein a gap of apredetermined size is formed between said covering means and said commonelectrode, said gap being fixed by said seal member.
 2. A radiationdetecting element comprising: a substrate having at least individualelectrodes corresponding to pixel areas; converting means, formed on animage area comprising said pixel areas, of converting radiation intoelectricity; a common electrode arranged on said image area andcorresponding to said individual electrodes; covering means of coveringsaid individual electrodes, said common electrode, and said convertingmeans and fixed to a surface of said substrate on which said image areais formed, the covering means having a three-layered structure in whicha non-moisture permeable layer is sandwiched between two other layers;and non-moisture permeable sealing means of sealing a peripheral portionof said covering means, and wherein: in the peripheral portion of saidcovering means, said sealing means and the non-moisture permeable layerof said covering means are in directly tight contact with each other. 3.A radiation detecting element comprising: a substrate having at leastindividual electrodes corresponding to pixel areas; converting means,formed on an image area comprising said pixel areas, of convertingradiation into electricity; a common electrode arranged on said imagearea and corresponding to said individual electrodes; non-moisturepermeable covering means formed only on said common electrode; andnon-permeable sealing means of sealing an area extending from aperipheral portion of said covering means to a surface of saidsubstrate.
 4. A radiation detecting element comprising: a substratehaving at least individual electrodes corresponding to pixel areas;converting means, formed on an image area comprising said pixel areas,of converting radiation into electricity; a common electrode arranged onsaid image area and corresponding to said individual electrodes; andnon-permeable sealing means of sealing an area extending from aperipheral portion of said common electrode to a surface of saidsubstrate, and in that: said common electrode has non-moisturepermeability.
 5. The radiation detecting element according to any ofclaims 1 to 4, wherein said converting means is a semiconductorphotoelectric conversion film.
 6. The radiation detecting elementaccording to claim 5, wherein said semiconductor photoelectricconversion film is amorphous selenium, iodide, bromide, or telluride, orany mixture thereof.
 7. The radiation detecting element according to anyof claims 1 to 4, wherein said converting means has a scintillator and aphotodiode.
 8. The radiation detecting element according to claim 7,wherein said scintillator has thallium-activated sodium iodide (NaI(Tl)), thallium-activated cesium iodide (CsI (Ti)), sodium-activatedcesium iodide (CsI (Na)),or bismuth gemanate (Bi₄Ge₃O₁₂), or any mixturethereof.
 9. The radiation detecting element according to any of claims 1to 4, wherein said covering means is glass.
 10. The radiation detectingelement according to claim 9, wherein said glass blocks ultraviolet raysand visible light of short wavelengths belonging to a blue area.
 11. Theradiation detecting element according to any of claims 1, 2, and 4,wherein said covering means has a layered structure.
 12. The radiationdetecting element according to claims 11, wherein said layered structureincludes a resin layer and a metal or glass layer.
 13. A manufacturemethod for a radiation detecting element comprising the steps of:forming at least individual electrodes corresponding to pixel areas, ona substrate; forming converting means of converting radiation intoelectricity, on an image area comprising said pixel areas; arranging acommon electrode corresponding to said individual electrodes, on saidimage area; providing a seal member disposed from a periphery of saidconverting means; fixing a non-moisture permeable covering on saidindividual electrodes, said common electrode, and said converting means,to a surface of said substrate on which said image area is formed; andproviding a gap of a predetermined size formed between said covering andsaid common electrode, said gap being fixed by said seal member.
 14. Amanufacture method for a radiation detecting element comprising thesteps of: forming at least individual electrodes corresponding to pixelareas, on a substrate; forming converting means of converting radiationinto electricity, on an image area comprising said pixel areas;arranging a common electrode corresponding to said individualelectrodes, on said image area; fixing a covering on said individualelectrodes, said common electrode, and said converting means, to asurface of said substrate on which said image area is formed, thecovering having a three-layered structure in which a non-moisturepermeable layer is sandwiched between two other layers; and sealing aperipheral portion of said covering using a non-moisture permeable seal,wherein: in the peripheral portion of said covering, said seal and thenon-moisture permeable layer of said covering are in directly tightcontact with each other.
 15. A manufacture method for a radiationdetecting element comprising the steps of: forming at least individualelectrodes corresponding to pixel areas, on a substrate; formingconverting means of converting radiation into electricity, on an imagearea comprising said pixel areas; arranging a common electrodecorresponding to said individual electrodes, on said image area; forminga non-moisture permeable covering only on said common electrode; andsealing an area extending from a peripheral portion of said covering toa surface of said substrate, using a non-permeable seal.
 16. Amanufacture method for a radiation detecting element comprising thesteps of: forming at least individual electrodes corresponding to pixelareas, on a substrate; forming converting means of converting radiationinto electricity, on an image area comprising said pixel areas;arranging a common electrode corresponding to said individualelectrodes, on said image area; and sealing an area extending from aperipheral portion of said common electrode to a surface of saidsubstrate, using a non-permeable seal, wherein: said common electrodehas non-moisture permeability.